Internal-combustion burner



June 1954 c. J. STALEGO 81, 95

INTERNAL-COMBUSTION BURNER Filed May 3, 1951 INVENTOR CHARLES 1514mm.

v L A ORNEYS.

Patented June 22, 1954 UNITED STATES PATENT OFFICE INTERNAL-COMBUSTIONBURNER Charles J. Stalego, Newark, Ohio, assignor to Owens-CorningFiberglas Corporation, a corporation of Delaware 12 Claims. 1

This invention relates to internal combustion burners and moreespecially to a burner construction of a character especially adaptablefor producing an intensely hot, high velocity gaseous blast suitable forattenuating heat softenable material to fibers.

Internal combustion burners have been employed to produce an attenuatingblast for forming glass fibers where a fiber of comparatively small sizeor diameter is desired. In burners of this character, the blast isformed by burning a combustible fuel and air mixture, preferably amixture of fuel gas and air, in a confined zone or chamber of theburner, the latter being provided with a relatively small or restrictedorifice through which the intensely hot products of combustion areexhausted at a high velocity for attenuating glass or other heatsoftenable fiber forming material to fine fibers.

A burner of this character is disclosed in Stalego Patent 2,489,243, andone exemplary use of the burner for fiber formation involvescontinuously feeding elongated bodies or primary filaments of glass intothe blast emanating from the burner in a direction substantially normalthereto whereby the advancing ends of the primary filaments are softenedand drawn or attenuated into fine fibers by the velocity of the blast inthe manner disclosed in the above mentioned Stalego patent.

Burners utilized for the stated purposes are subjected to exceedinglyhigh temperatures being upwards of three thousand degrees Fahrenheit andsuch temperatures require the utilization of heat resisting refractorymaterials in the burner construction. The available refractoriesemployed for the purpose are nevertheless subject to thermal shock andwhile the coefficient of expansion of such refractory materials iscomparatively low, due to the thermal shock resulting from the widerange of temperatures encountered, the useful life before fractureultimately occurs is comparatively short, being usually a matter of afew days.

It has been conventional practice in constructing such burners to employa high temperature refractory at the orifice or blast discharge end ofthe burner having comparatively thick wall areas to provide thenecessary strength to withstand the gas pressures developed duringcombustion and to minimize heat losses through radiation. Thetemperatures in the zone of the nozzle are usually between twenty-fourhundred degrees and three thousand degrees Fahrenheit, while thetemperature of theouter zone or perimeter of the wall may beapproximately two thousand degrees Fahrenheit or less. While the thickwalls adjacent the orifice are effective to withstand the gas pressuresand minimize heat losses through radiation, they are however readilysubject to thermal shock or expansion and ultimate fracture whereby thelongevity of such burner under continuous operation as encountered inthe attenuation of glass to fibers rarely exceeds a period of fromfifteen to twenty days.

The present invention embraces a burner embodying a member of refractorymaterial formed with a nozzle or blast orifice the walls of which areconfigurated to minimize or reduce the liability of the refractory tofracture under the stresses or thermal shock existent under hightemperature operation.

An object of the invention is the provision of a member provided with anorifice suitably arranged to facilitate flow of gases therethrough inthe form of a high temperature, high velocity blast, the walls of themember being configurated in a manner to reduce or minimize the internalstresses resulting from expansion and contraction under extremevariation in operating temperatures.

Another object of the invention resides in the provision of an orificeconstruction fashioned of refractory material for incorporation in ablast producing internal combustion burner wherein relatively thickwalled portions of the refractory are slotted or relieved in a manner toreduce the molecular stresses or internal pressures generated by reasonof the high temperatures of the burned gases whereby the tendency orliability for the refractory to fracture or fail in operation is greatlyreduced and the life thereof correspondingly increased effectingmaterial savings in the cost of fiber attenuating operations.

Another object of the invention resides in the provision of a nozzle ororifice construction for use under extremely high temperatures ofburning gases shaped or configurated in a manner to reduce the stressesarising by reason or" temperature diiferential existent between thethroat of the nozzle or orifice and the exterior zones of the refractorymaterial without sacrificing the strength characteristics necessary towithstand the pressures developed by combustion.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, operation and function of the relatedelements and to combinations of parts, elements per se, and to economiesof manufacture and numerous other features as will be apparent from aconsideration of the specification and drawing of a form of theinvention, which may be preferred, in which:

Figure 1 is a semidiagrammatic elevaticnal view illustrating theutilization of a form of the invention for producing a blast of gases ofcombustion adapted for the attenuation of heat softenable fiber formingmaterials;

Figure 2 is an elevational view of a burner construction embodying theinvention, certain portions being shown in section for purposes ofillustration, and

Figure 3 is an end elevational view of the construction illustrated inFigure 2 particularly showing the configuration of refractoryconstruction defining the blast orifice.

While the embodiment of the invention disclosed is of a characterparticularly useful in apparatus for producing very fine fibers throughthe attenuation of fiber forming material fed into an intensely hotgaseous blast, it is to be understood that the orifice constructionembcdying the principles of this invention may be utilized to advantagewith other types of burners or combustion devices where comparativelyhigh temperatures are encountered.

Referring to the drawings and first with re spect to Figure 1, there isillustrated an apparatus for attenuating fibers from fiber formingmaterials such as glass utilizing a blast producing burner embodying theinvention. The arrangement illustrated includes a receptacle orforehearth H] adapted to contain a supply of molten fiber formingmaterial such as molten glass. Disposed beneath the receptacle is is afeeder !2 formed with a plurality of small orifices or outletsforfiowing or feeding a plurality of streams S of the'molten material.The streams 3 moving downwardly are substantially solidified by thecooling effects of the surrounding atmosphere and are gathered togetherand directed between feed rolls M; which serve to draw the streams intoprimary filaments.

The filaments or rods F so formed are directed by a suitable guide itinto a blast B projected from a restricted orifice formed in a forwardwall or nose portion of a combustion burner 20. The burner 26 is formedwith a chamber 22 in which a combustible mixture of gaseous fuel and airis burned, the burned gases being discharged through an orificeproviding an intensely hot, high velocity blast which engages theadvancing ends of the primary filaments F moving into the blast, theheat of the blast softening the advancing ends which are continuouslyattenuated or drawn out to fine fibers by the force and velocity of theblast.

The attenuated fibers are conveyed by the blast to a collecting zonepreferably including a movable foraminous conveyor 24 mounted uponsupporting rollers 26. The forward flight of the conveyor forms a'collecting surface upon which the attenuated fibers pile up oraccumulate in a mat formation which is continuously removed from thecollecting zone by the. conveyor. A chamber 28 disposed rearwardly ofthe forward fiight of the conveyor is connected with a source of reducedpressure or suction to facilitate the adherence and collection of thefibers upon the conveyor.

The burner construction for producing the high velocity attenuatingblast for fiber forming purposes is inclusive of a metal shell 34suitably adapted and shaped to enclose a refractory wall 4 construction36 preferably composed of two telescopically arranged elements or layers3'? and 38, the multi-layer construction facilitating expansion andcontraction attendant the wide temperature changes and variationsencountered in the burner. The burner is formed with a transverse wall40 containing a plurality of perforations or apertures 42 for admittinga combustible mixture to the chamber 22 through a duct in the fitting 35secured to a flange associated with the burner shell 34. The fitting 45may be connected by means of a tube 48 with a supply of fuel gas mixedwith air in the proper proportions to form an eflicient combustiblemixture.

The burner construction is provided at its forward end with a member 59formed with an orifice 52 through which the intensely hot gases ofcombustion from the combustion chamber 22 are projected in the form ofan intensely hot, high velocity blast B. As shown in Figure 3, theorifice is preferably elongated in a horizontal direction to accommodateor overreach the plurality of primary filaments F which areconcomitantly fed into the blast in side by side relation. The member 50is formed of a high temperature resistant refractory material of acharacter adaptable to withstand the temperatures of the hot gasesprojected through the orifice 52.

Heretofore theorifice member of a conventional burner has been formedwith comparatively thick wall portions which were readily amenable tothermal shock and which usually fractured after a comparatively few daysof use. The orifice member of the present invention is configurated in amanner providing adequate strength to withstand the pressures of theburning gases within the chamber and adjacent the orifice and which isshaped to reduce or substan-- tially eliminate the liability to fractureunder thermal shock. As particularly shown in Figure 3, the peripheralportion of the member 50 is configurated with a plurality of spacedperipheral segments 51 formed by radially arranged kerfs or slots 58separating the segments. The contour of the orifice 52 is therebybounded or embraced by a wall portion which is continuous, the outerportion of which is peripherally relieved of extreme molecular stressesthrough the presence of the radial slots. Thus under the extremelyhightemperatures encountered in the burning gases, the wall portion 60being of reduced thickness may readily expand and contract under thermalshock with comparative ease and facility without liability of fracturingbecause the temperature differential in and throughout the wall or zoneportion 60 surrounding the orifice is substantially uniform and hencestresses or forces are minimized or reduced which would otherwise tendto fracture the member 50.

Through the provision of the segmental formation of the peripheral areasor zones of member 50, expansion and contraction of the segments isreadily accommodated through the presence of the radial slots 58 so thateven though the expansion and contraction under wide temperaturevariations ensues in the segments 51, the circumferentially directedstresses are greatly reduced because of lack of continuity of the thickwall area and hence the comparatively thin wall portion at 60 boundingordefining the orifice may expand a greater amount than the segmentswhereby the tendency of the orifice wall to fracture is minimized orsubstantially'eliminated through the facility that the segments arevirtually permitted expansion and contraction independently of the thincontinuous wall portion 66 adjacent the orifice. While the presence ofthe radial slots 58 subdivides the peripheral portions of the member 50,the radial thickness of the segments provides the necessary strengthcharacteristics in radial directions from the orifice to withstand thepressure of the gases at the zone of the orifice.

It has been found that the construction of the orifice plate or memberin the manner hereinbefore described provides an arrangement whereby thelife of the burner is many times that of constructions heretofore usedwhich were amendable to fracture after a short period of use.

It is apparent that, within the scope of the in vention, modificationsand difierent arrangements may be made other than is herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

What I claim is:

1. A burner of the character disclosed adapted to burn a combustiblemixture in a confined zone, said burner having a restricted orificethrough which intensely hot gases of combustion are projected as a highvelocity blast; the portion of the burner provided with the orificebeing formed of high temperature resistant refractory material andhaving a relatively thin wall portion defining the orifice and a thickwall portion formed rearwardly of the orifice, said thick wall portionhaving peripherally spaced-apart areas of reduced thickness forminimizing thermal shock in the refractory material.

2. A burner of the character disclosed adapted to burn a combustiblemixture in a confined zone, said burner having a restricted orificethrough which intensely hot gases of combustion are projected as a highvelocity blast; the portion of the burner provided with the orificebeing formed of high temperature resistant refractory material having athin wall defining the orifice and progressively increasing in thicknessrearwardly into a relatively thick wall, said thick wall being formedwith peripherally spaced recesses for minimizing thermal shock in therefractory material.

3. A. burner of the internal combustion type adapted to burn acombustible mixture in a confined zone for producing a blast ofintensely hot gases of combustion; the interior of the burner beinglined with refractory material, said burner having a nose portion formedof refractory material and provided with an orifice through which thegases of combustion are projected as a blast; the wall bounding the exitof the orifice being continuous and relatively thin, the refractorymaterial adjacent and rearwardly of the orifice being relatively thick,the peripheral 'zone of said relatively thick portion being reduced incross section at spaced zones to interrupt the peripheral accretion ofmolecular stresses of expansion and contraction.

4. A. burner of the internal combustion type adapted to burn acombustible mixture in a confined zone, said burner being provided witha restricted orifice through which intensely hot gases of combustion areprojected as a high velocity blast; the interior of the burner beinglined with refractory and the orifice being formed in refractorymaterial; the wall defining the orifice being relatively thin; therefractory wall portion adjacent and rearwardly of the orifice beingrelatively thick, the periphery of said 6 thick wall portion beingformed with spaced radially disposed slots providing spaced zoneswhereby the stresses of expansion and contraction resulting fromtemperature changes are localized in said zones.

5. A burner adapted to burn a combustible mixture in a confined zone,said burner being provided with an orifice through which the products ofcombustion are projected as an intensely hot, high velocity blast; theinterior walls of the burner being lined with refractory material; ablock of high temperature resistant refractory material at the forwardend of the burner and in. which the orifice is formed, the wall portionof the block at the forward end of the orifice being comparatively thinand progressively increasing in thickness in a direction rearwardly ofthe orifice, the portion of greater thickness being peripherallyrecessed at spaced zones to reduce thermal shock.

6. A burner adapted to burn a combustible mixture in a confined zone,said burner being formed with an orifice through which the prodnets ofcombustion are projected as an intensely hot, high velocity blast; theinterior walls of the burner being lined with refractory material; ablock of high temperature resistant refractory material at the forwardend of the burner and in which the orifice is formed, the wall portionof the block. at the forward end of the orifice being comparatively thinand of increased thickness rearwardly of the orifice, the portion ofincreased thickness being formed with radially disposed, peripherallyspaced recesses forming sections in which the stresses of expansion andcontraction occurring the the thickened wall are isolated whereby thetendency of the wall to fracture is substantially minimized.

7. A burner adapted to burn a combustible mixture in a confined zone,said burner being provided with a transversely elongated orifice throughwhich the products of combustion are projected as an intensely hot, highvelocity blast; the interior walls of the burner being lined withrefractory material; a member of high temperature resistant refractorydisposed at one end of the burner and formed with the orifice ofelongated shape to provide a ribbon-like blast; the wall defining theexit zone of the or'mce being relatively thin and progressivelyincreasing in thickness to substantially circular configuration in adirection rearwardly of the orifice; the portion of substantiallycircular configuration being formed with peripherally spaced slots toinhibit the cumulation of stresses of thermal shock in the relativelythick portion of the member resulting from the high temperatures of thegases in the blast.

8. A member of refractory material for use with a moving stream ofintensely hot gases having an orifice defining the cross-sectionalcontour of the gas stream, said member being formed with a comparativelythin wall bounding the exit zone of the orifice and a thickened wallpertion spaced from the exit zone, said thickened wall being formed withperipherally isolated portions for minimizing the stresses resultingfrom thermal shock.

9. A member of refractory material for use with a moving stream ofintensely hot gases having an orifice defining the cross-sectionalcontour of the gas stream, said member being formed with a comparativelythin wall bounding the exit zone of the orifice and a thickened wallportion spaced rearwardly from the exit zone,

being lined with refractory material; a mem- V ber of refractorymaterial disposed at one end of the burner and formed with the orificeelongated in a transverse direction to provide a ribbon-like blast; thewall defining the orifice being relatively thin at the exit zone andprogressively increasing in thickness to substantially circularconfiguration in a direction rearwardly of the orifice; the circularconfiguration being formed with peripherally spaced radially arrangedslots forming isolated sections inhibiting the accretion in thethickened wall portion of molecular stresses set up by the temperaturedifferential existent between the relatively thin and thickened wallsadjacent the orifice.

11. A burner of the internal combustion type adapted to burn acombustible mixture in a confined zone, said burner being provided witha restricted orifice through which intensely hot 9 gases of combustionare projected as a high velocity blast; the interior of the burner beinglined with refractory material, the Wall of refractory material definingthe orifice being relatively thin and the Wall of material rearwardly ofthe orifice being relatively thick, said thick wall portion being formedwith spaced-apart areas of reduced thickness at its exterior zone toinhibit the accretion of molecular stresses occurring under hightemperatures whereby tendency of the material to fracture issubstantially reduced.

12. A burner adapted to burn a combustible mixture in .a confined zone,said burner being formed with an orifice through which the products ofcombustion are projected as an intensely hot, high velocity blast; theinterior walls of the burner and the portion thereof in which theorifice is formed being of a high temperature resistant refractorymaterial, a zone of the refractory disposed adjacent and rearwardly ofthe orifice being relatively thick and having its exterior peripheryformed with spaced-apart areas of reduced thickness providing forsubstantially unrestricted expansion and retraction of the refractory inthe exterior zone without materially reducing the strength of therefractory material bounding the orifice.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,559,527 Williams July 3, 1951 2,561,200 Hess July 17, 1951

